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Title: Subfunctionalization of sigma factors during the evolution of land plants based on mutant analysis of liverwort (Marchantia polymorpha L.) MpSIG1.
Authors: Ueda, Minoru
Takami, Tsuneaki
Peng, Lianwei
Ishizaki, Kimitsune
Kohchi, Takayuki  kyouindb  KAKEN_id  orcid (unconfirmed)
Shikanai, Toshiharu  kyouindb  KAKEN_id
Nishimura, Yoshiki  kyouindb  KAKEN_id  orcid (unconfirmed)
Author's alias: 西村, 芳樹
Keywords: chloroplast transcription
plastid-encoded RNA polymerase
gene duplication
Issue Date: 11-Sep-2013
Publisher: Oxford University Press
Journal title: Genome biology and evolution
Volume: 5
Issue: 10
Start page: 1836
End page: 1848
Abstract: Sigma factor is a subunit of plastid-encoded RNA polymerase that regulates the transcription of plastid-encoded genes by recognizing a set of promoters. Sigma factors have increased in copy number and have diversified during the evolution of land plants, but details of this process remain unknown. Liverworts represent the basal group of embryophytes and are expected to retain the ancestral features of land plants. In liverwort (Marchantia polymorpha L.), we isolated and characterized a T-DNA-tagged mutant (Mpsig1) of sigma factor 1 (MpSIG1). The mutant did not show any visible phenotypes, implying that MpSIG1 function is redundant with that of other sigma factors. However, quantitative reverse-transcription polymerase chain reaction and RNA gel blot analysis revealed that genes related to photosynthesis were downregulated, resulting in the minor reduction of some protein complexes. The transcript levels of genes clustered in the petL, psaA, psbB, psbK, and psbE operons of liverwort were lower than those in the wild type, a result similar to that in the SIG1 defective mutant in rice (Oryza sativa). Overexpression analysis revealed primitive functional divergence between the SIG1 and SIG2 proteins in bryophytes, whereas these proteins still retain functional redundancy. We also discovered that the predominant sigma factor for ndhF mRNA expression has been diversified in liverwort, Arabidopsis (Arabidopsis thaliana), and rice. Our study shows the ancestral function of SIG1 and the process of functional partitioning (subfunctionalization) of sigma factors during the evolution of land plants.
Rights: © The Author(s) 2013. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (, which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited.
DOI(Published Version): 10.1093/gbe/evt137
PubMed ID: 24025801
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